Hoisting mechanism



April 1953 P. F. BLACKMAN ETAL ,633,999

HOISTING MECHANISM 2 SX-IEETS-SHEET 1 Filed July 6, 1948 mmvrons PAUL F. BLAGKMAN EDWIN N. BLAGKMAN w. SHIPP o ffi AI IORIZEYS April 7, 1953 P. F. BLACKMAN ETAL 2,633,999

HOISTING MECHANISM Filed July 6, 1948 2 SHEETS-SHEET 2 'IIIIIIII 'IIIIIIIIIIIIIIIII I- 11111 INVENTORS PAUL F. BLAGKMAN EDWIN N. BLAOKMAN JAN W. SHIPP M ATTORNEYS Patented Apr. 7, 1953 HOISTING MECHANISM Paul F. Blackman, Edwin N. Blackman, and Jan W. Shipp, Los Nietos, Calif.; said Edwin N. Blackman and said Jan W. Shipp assignors to said Paul F. Blaekman Application July. 9, 1948, Serial No.'37,246 2 Claims. (01. 212-8) The present invention relates to an improved hoisting arrangement particularly useful, but not limited in its use, in loading and unloading heavy objects from a truck.

An object of the present invention is to prooil field operations.

A further object of the present invention is to provide an improved hoisting mechanism comprising relatively few parts which may be easily manufactured and assembled by the use of present-day mass production methods and expedi ents.

A further object of the present inventionis to provide an improved hoisting mechanism. in

, which the'stress carrying members are subjected substantially only to tension and compression forces in hoisting operations with substantially no bending forces on such members.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be bestunderstood by reference to the following description taken in connection with the accompanying drawings in which: 7

Figure 1 is a view of a hoisting mechanism mounted on a truck in operative position to raise an object from the ground onto the truck platform upon which the mechanism is mounted.

Figure 2 is a view; similar to the view shown in Figure 1 but with the mechanism in position when,

the object is raised above the ground.

Figure 3' is a view similar to the view shown in Figure 1 with the parts of the hoisting mechanism in position :after such object is placed on the truck platform.

Figure 4 is an elevational view showing the hoisting mechanism in its lower position in solid lines and in its upper position in dotted lines illustrating the manner in which the parts move relative to each other.

This invention Figure 5 is a sectional view taken substantially on the line 5-5 of Figure 4.

Figure 63 is a view in elevation taken in the direction indicated by the arrows 6-45 in Figure 4.

Figure 7 is an enlarged cross-sectional view taken substantially on the line 1-1 of Figure 4.

Figure 8 is a view similar to Figure '7 and shows the manner in which the hoisting parts are maintained in the position shown in Figure 3.

The hoisting mechanism comprises a frame which includes a center leg I and two side legs 8, 9 each pivotally connected to the truck deck or platform P at 1A, 8A, and 9A, respectively. The center leg 1 comprises in fact an inner telescopic member H which is pivotally connected at 1A and an outertelescopic member l2 which has a sheave block l3 mounted on its upper end. 'The inner telescopic member H is referred to as a boom. This sheave block I3 is pivotally connected to the upper ends of the side legs 8, 9. Outward movement of the outer sleeve member I2 is prevented by the stop member ID mounted on the upper end of the inner telescopic member II. The length of the outer center leg I2 determines, as will be more evident as this description progresses, the horizontal travel of the sheave block [3 over the deck P of the truck.

The sheave assembly l3 consists of a steel bronze bushed wheel BA, and the block |3Bis of steel plate welded to the upper end of the outer center leg l2. The wheel I3A is held in position and rotates on the same steel pin I30 whichv secures the side legs 8, 9 to the sheave block I3B.

The outer sleeve member I2 is adapted to contact the ring l5 in its downward movement on member H to compress the coil buffer spring 16 which. is suitably housed in the hollow cylindrical casing ISA mounted on the inner member ll. Such downward movement of the outer sleeve member I2 is limited when the ring member 15 having the integrally formed cylindrical portion [5A engages the inner casing wall at 16B.

This cylindrical portion 15A thus cooperates with the wall at l6B to'form a stop preventing excessive compression of the spring l6 when the outer sleeve member I2 is moved downwardly. This spring I6 is a heavy duty compression spring and serves to cushion the shock on this hoisting mechanism in loading and unloading operations and also to start movement of the load in the initial stage of the unloading operation as will be described in more detail hereinafter. Normally, this compression spring I6 is prestressed to normally urge the outer sleeve member 12 against the stop member I on the inner sleeve member H.

A flexible cable 20 passes over the rotatable element or wheel 13A in the sheave assembly [3 and also over the power-driven winch 2|. This winch 2! may be of conventional structure and may be driven in conventional manner and is rotatably supported on the truck platform. This cable 26 has mounted thereon an abutment or stop 22 arranged to cooperate with the re-en.- trant portion 23 in the sheave block to produce relative movement of the outer sleeve member [2 with respect to the inner sleeve member II, as is described in more detail hereinafter.

Referring to Figure 1, in the initial stage of the loading operation the winch drum is operated to wind the flexible cable 20 thereon, the free end of the cable 29 being, of course, attached to the apparatus A which is to be hoisted onto the platform P of the-truck. When and as the cable 20 is taken in by' the winch, the object A travels vertically until the stop member 22' on the line 20 contacts the re-entrant portion 23-- of the sheave block. Thereafter, the sheave assembly 13 mounted onthe outer telescopic member I 2- is moved toward the front of the truck, causing the inner center leg H to raise while the outer'oenter leg l2 follows the same are as the side legs 8, 9 to thereby cause the'l-oador object A to travel in a. general horizontal path over the bed of the truck: During suchmovement of s'leeve'memb'er' 12.: on the inner member H the coil compression spring Hi is progressively stressed and serves. as a buffer to absorb any shock' forces. moves the required distance'toposition the object A over the platform P of the truck; the operator inserts a removable pin 3ilithr'ough matched or'aligned'holes HS, IZS in the telescopic members H, 12, respectively, to thereby maintain: the compression spring H5 in its compressed state to allow subsequent slacking of the cable 20 and lowering of the object A onto the platform P of the truck.

To thereafter unload the object A from the platformof the truck onto the ground, the winch is operated to raise the object A and to bring the stop member 22 in engagement with the reentrant portion 23 of the sheave block after which the'pin is withdrawn from the aligned holes I IS, IZS whereupon the stored energy in the spring Hi causes the outer sleeve member l2 to move outwardly on the inner" sleeve member H, simultaneously moving with it the object A to a position where the object A may be directly loaded onto the ground; this'position corresponds to the position wherein the outer sleeve [2 contacts the stop member to limit such outward movement. When the outer sleeve-member [2 thus engages the stop Hi, the mechanism is in the down position and the loadA may then be lowered onto the ground or a loading dock by releasing the winch.

In the normal position, as, shown inv Figure 1,

it is noted that the inverted V'-shapedframe comprising the frame members 8, 9 having the sheave assembly [3 pivotally mounted at the apex of said V-shaped frame has gravity forces acting thereon tending to rotate such sheave away from the truck bed about the pivotal connections 8A, 9A, but such movement of the sheave which would otherwise be produced by gravity forces acting thereon, is limited by the cooperating stop means Ellinterposed between the rela- When the outer sleeve member I2 tively movable telescopic members H, I2. Thus, the frame members of the hoisting mechanism in Figure 1 are normally maintained in position shown therein by the action of gravity forces acting on the frame members and without any action of the coil compression spring l6 which only becomes compressed during the final stage of the loading operation.

While the particular embodiments of the present invention have been shown and described, it Will be obvious to those skilled in the art that changes and modifications may be made Without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications-as fall within the true spirit and scope of this invention.

We claim:

1. A hoisting mechanism comprising a single pair of elongated side frame members, a sheave assembly incorporating a rotatable member, a support, said frame members being each arranged to have one of its ends pivotally mounted on said support and its other'end pivotallyconnected to said sheave assembly, a centrally disposed pair of telescopic members centrally mounted with respect to said side members, the outer one of said telescopic members being affixed to said sheave assembly, the'inner one of said telescopic members being arranged for pivotal movement'on said support, a flexible cable passing over said rotatable member and through said sheave assembly and having a stop member thereon for engagement with said assembly, said cable having a reach extending generally parallel with said pair of telescopic members, and power operated means to reel in said cable to thereby move said stop member into engagement with said sheave assembly to move said assembly with respect to the inner one of said telescopic members, said inner one of said telecopic member extending all the way through said outer telescopic member and having an enlarged stop member thereon cooperating with that end of the outer telescopic'member which is adjacent said sheave assembly.

2. A hoisting mechanism comprising a single pair of elongated side frame members, a' sheave assembly incorporating a rotatable member, a support, said framemembers being each arranged to have one of its ends pivotally mounted on said support and its other end pivotally connected to said'sheave assembly, a centrally disposed pair of telescopic members centrally mounted with respect to saidside members, the outer one of said telescopic members being affixed to said sheave'assembly, the inner one of saidtelescopic members being arranged-for pivotal movement on said support, a flexible cable passing over said rotatable member and through said sheave assembly and having a stop member thereon for engagement with said assembly, said cable having. a reach. extending generally parallel with said pair of telescopic members, and power operated means to reel. in said cable to-thereby move said stop member into engagement with said sheave assembly to movesaid assembly with respect to the inner one of said telescopic members, said inner telescopic member having-mounted thereon a hollow cylindrical casing, a buffer spring encircling said inner telescopic member and disposed within said casing, a ring encircling said inner telescopic member and disposed between, on. the one hand, said spring, and on the other hand, said casing, said ring being adapted for contact by the outer telescopic member, a. cylindrical portion affixed to said ring and 00- REFERENCES CITED The following references are of record in the 10 file of this patent:

UNITED STATES-PATENTS operating with an end wall of said casing to Number Name Date prevent undue stressing of said spring. 1,019,268 Melzer "1... Mar. 5, 1912 PAUL BLACKMAN- 5 1,658,873 Younkman et a1. Feb. 14, 1928 EDWIN N. BLACKMAN. 1,373,433 Larsen Aug. 23, 1932 JAN W. SHIPP. 2 257,373

Troche Oct. '1, 1941 

